Getting a better resolution with MPX2010DP

[GHernan]

Hi, im using a MPX2010DP pressure sensor, Sourcing with 15v from 7815 regulator,  ADC 10bits built-in  pic18f4550, between sensor and pic there is a INA128 Instrumentation Amplifier, gain= 133,3, R= aprox 373 ohms, the resolution I've get now its about 100pascales, or in water column --> 1cm= 0.3937 in, I've got a 100mV of noisy signal, this resolution its after making an average by software of 64 samples from the adc, if i could get a better resolution it would be great, somebody worked with this sensor and got more resolution? i was trying to minimize de noise but i couldnt yet, maybe a should use another sensor.  Thanks!.

[Joshevelle]

Hello Guillermo,

Thanks for using our community.

The resolution you already have is very good, I would recommend you to implement a low pass filter at the output of the sensor to reduce the noise.

Please notice that the MPX2010 has a resolution of 2.5mV/kPa (page2, table1 of the datasheet). Which means that you're trying to measure 250uV ((2.5mV/kPa) * (1kPa/1000Pa)*(100Pa)). The sensor has a Vo full scale span of 25mV, hence the 250uV that you're measuring equals to 1%Vfss _AND_ the MPX2010 has a linearity of +-1%. Hence, the measurements you're reading could be inaccurate.

What is the maximum pressure in your application? you could use the MPXx5004, which has a better resolution (1V/kPa) but has a lower pressure range (0-3.92kPa) and is an integrated pressure sensor, therefore you would not require the instrumental amplifier anymore:

http://cache.freescale.com/files/sensors/doc/data_sheet/MPXV5004G.pdf

hope it helps.

-Josh